Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

unwanted reflections from lightsource

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capebio
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unwanted reflections from lightsource

Post by capebio » 14 Jul 2013, 17:10

I have my 10 watt LED floodlight positioned in the centre of the standard Reetz build (picture of it here: http://casabio.blogspot.com/2013/06/vir ... first.html).

At first I was getting reflections from the silver A4000IS camera. I then used double sided tape to stick black magazine paper over the front of the camera, with a separate ring of black paper for the moving lens.
I then took a photo, and surprise surprise, there was another reflection. As I lowered myself to the level of the camera to see what was causing it, I saw the reflection of the floodlight hove into view.
Surely this is a fundamental flaw of the basic design? Everything is standard: The direction of the glass, the level of the cameras, the position of the light.
Besides cleaning the glass, what can I do?

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jbaiter
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Re: unwanted reflections from lightsource

Post by jbaiter » 15 Jul 2013, 03:54

I think I'm using the exact same floodlight and I only get a very small reflection on the upper edge of the images that doesn't have any negative impact on the scans per se. Maybe you could try propping up your lighting unit so the distance between the glass and the light increases?
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capebio
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Re: unwanted reflections from lightsource

Post by capebio » 15 Jul 2013, 10:29

I tried raising the light, but it only made a very minor difference, because ultimately it gets obscured by the walls of the light mounting.
Would making the lightsource diffuse make any difference? It was one suggestion I received.

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jbaiter
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Re: unwanted reflections from lightsource

Post by jbaiter » 15 Jul 2013, 11:47

Do you have an example scan with the reflection?
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rkomar
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Re: unwanted reflections from lightsource

Post by rkomar » 15 Jul 2013, 13:37

Are you sure the reflection is coming from the LED?

Making the light diffuse wouldn't help in this case. It might help make it more even on the book, but it wouldn't reduce reflections. It would probably make it worse because the diffuser would be much larger than the LED.

dpc
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Re: unwanted reflections from lightsource

Post by dpc » 15 Jul 2013, 15:40

You can also move the camera farther away from the platen and zoom in.

A picture taken of a solid black page under the glass would help understand what is going on.

powercircuits
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Re: unwanted reflections from lightsource

Post by powercircuits » 21 Feb 2015, 01:00

Glare off of smooth glass is all about angles. The light will bounce directly off the glass into the camera in a straight line. You need to shift the light source, glass, or camera around so there is not a direct line of sight between them.

For example if the glass were horizontal with the camera directly above, you would want the light shining down at around a 45 degree angle so that it reflects off towards the other side of the camera. You can add additional lights coming in from different directions (but never bouncing directly into the camera) to even out the lighting.

If the glass were a mirror and you put your eye where the camera lens is, you shouldn't be able to see the light bulbs directly or else you will pick up a glare.

wambold
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Re: unwanted reflections from lightsource

Post by wambold » 12 Mar 2015, 10:39

I have the same kit and two silver Canon cameras. I did two things:

Switched to anti-reflective glass. I think I've seen some posts that recommend against AF glass but I got all sorts of glare otherwise. I went to Aaron Brothers, they had museum glass in pre-cut in exactly the right size for the scanner kit.

Made the cameras black. I used Scotch Expressions Washi Tape in black. It's a nice thin tape that generally conforms well to the surface of the camera. It took a while, with lots of small cuts of tape, but I now have two black front cameras.

I'm going to be adding more lighting. I think the kit light just isn't bright enough. I don't know what I'm going what or how I'm going to add more lights though.

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